GPU being under utilized, and frame rate suffering as a result

When running the snapshot with 3 GB of RAM allocated and a view distance of 32 chunks, the game only manages to reach ~35 FPS when looking out into the distance. I checked my GPU usage and it was only at 33% utilization. CPU was at a similar level. Minecraft had only allocated half of the RAM available to it.
VSync was on, framerate limit was set to unlimited. Graphics settings in minecraft at maximum.